[Lxc-users] Lucid host & container - ignored fstab?

[Daniel Lezcano]

Roman Yepishev wrote:
> Hello, Daniel.
> Thanks for your reply!
>
> On Sun, 2010-04-11 at 09:41 +0200, Daniel Lezcano wrote:
>
>   
>> When the container starts, it setup the root filesystem. The rootfs is 
>> done with the pivot_root syscall, hence the old rootfs contains the 
>> mount points which are duplicates with the new rootfs. The code then 
>> umount these duplicates entry in the old rootfs without impacting the 
>> mount points of the new rootfs.
>>     
> Ok, this makes sense.
>
>   
>> The mount point specified in the configuration file is setup by lxc 
>> without using the "mount" command, so the /etc/mtab is not updated 
>> (which is normal). If you want to check if the mount point is 
>> effectively setup, you should check against /proc/mounts.
>>     
>
> Unfortunately it looks like /proc/mounts provides the same info as the
> mount command for me - 
> /dev/mapper/fridge-srv / ext4 rw,relatime,barrier=1,data=ordered 0 0
> none /dev/console\040(deleted) devpts rw,nosuid,noexec,relatime,gid=5,mode=620,ptmxmode=000 0 0
> none /dev/tty1\040(deleted) devpts rw,nosuid,noexec,relatime,gid=5,mode=620,ptmxmode=000 0 0
> none /proc proc rw,nosuid,nodev,noexec,relatime 0 0
> none /sys sysfs rw,nosuid,nodev,noexec,relatime 0 0
> none /sys/fs/fuse/connections fusectl rw,relatime 0 0
> none /sys/kernel/debug debugfs rw,relatime 0 0
> none /sys/kernel/security securityfs rw,relatime 0 0
> none /dev/pts devpts rw,nosuid,noexec,relatime,gid=5,mode=620,ptmxmode=000 0 0
> none /dev/shm tmpfs rw,nosuid,nodev,relatime 0 0
> none /var/run tmpfs rw,nosuid,relatime,mode=755 0 0
> none /var/lock tmpfs rw,nosuid,nodev,noexec,relatime 0 0
> none /lib/init/rw tmpfs rw,nosuid,relatime,mode=755 0 0
>
> So the entries from the lxc.mount fstab:
>
>  /srv/vm/lxc/lemon/rootfs /srv/vm/lxc/rootfs none bind 0 0
>  /var/cache/apt	   /srv/vm/lxc/lemon/rootfs/var/cache/apt none bind 0 0
>
> do not appear to be effective.
> I tried creating the file in /var/cache/apt of the container and it did
> not appear in the host filesystem so it looks like they are really
> separated.
>
> Is there anything that can be done to debug this problem?
> And even more interesting, is there anybody else experiencing such kind
> of issue?
>   

I was not able to reproduce the problem with the git head.
Maybe the problem was fixed between the 0.6.5 and the git head, but I 
don't see what commit it could be.

What looks weird is you have the log saying the directory was 
effectively mounted.
Is it possible the container's distro unmounts this directory ?

Can you check by doing 'lxc-start -n lemon /bin/bash' ?
We get ride of the system init script and you can check the content of 
/proc/mounts, that will give a clear idea of where is coming from the 
problem (lxc or os). BTW, you will have to mount /proc in the container.

Thanks
  -- Daniel